BACKGROUND: For a drug to be available for prescription by physicians, it must first undergo testing to demonstrate that it is effective in achieving its intended benefit and that any serious adverse side effects are characterized. If the Food and Drug Administration (FDA) approves a drug for use based on its assessment of the evidence, it can then be prescribed. Postmarketing surveillance is a term used to describe the process of monitoring for adverse side effects of a drug after it has been approved. Through the process of postmarketing surveillance, adverse side effects may be detected that escaped notice in the experimental studies (i.e., randomized trials) to test a drug's effectiveness. This exercise is based on an example of postmarketing surveillance. The specific drug considered in this exercise is tramadol hydrochloride, which is marketed under the trade name Ultram. In 1995, the FDA approved this drug for use in the United States as a non-scheduled drug, meaning that it was available by prescription. This medication is used to help alleviate moderate to severe pain. However, the FDA also realized that tramadol hydrochloride could potentially be abused because it can be highly addictive and because it acts on opioid receptors. The medication had previously been approved for use in Europe.

QUESTION (2 PARTS):

(1) In Europe, 8,145 persons who used tramadol hydrochloride were interviewed, and 122 reported that they abused the drug. Based on these data, calculate a measure of disease frequency to characterize how common tramadol hydrochloride abuse in Europe was. [Use units per 100]

(2) Do you consider your calculation to be incidence or prevalence? Why?